Meanwhile, the exact causes of autism remain a mystery. In the past three years, researchers at Yale, UCLA, and Johns Hopkins have all concluded that it's a disorder of the brain's synapses; the molecules active in an autistic person's synapse don't function properly. A 2009 study noted that the number of autism diagnoses rose 57 percent between 2002 and 2006, which signals to many experts that new environmental factors may increase the odds of developing these dysfunctional synapses. Research from the California Department of Public Health has indicated that advancing maternal age may play a role. Prematurity has been implicated, as has the timing of pregnancy: A recent study found that a second child conceived within a year of an older sibling's birth was more than three times as likely to be diagnosed with autism as children conceived more than three years after the birth. A child's exposure to pesticides and parents' medical conditions, including type 1 diabetes and rheumatoid arthritis, also are under study as possible factors.
While the 1998 study linking the MMR vaccine to autism has been completely discredited, Dawson does not want to dismiss concerns about vaccines entirely. Autism Speaks earmarks 2 percent of its research budget to vaccine studies. The National Institutes of Health, too, has called for more research, given that certain children appear to be more vulnerable than others to vaccine side effects.
BRAIN CANCER: New and better weapons
Each year, more than 22,000 people nationwide develop brain cancer, and more than half die, usually within 15 months. But researchers say they are now poised to make major breakthroughs. "Our understanding of brain tumors, and the way we think about treating them, has changed dramatically after decades of very little progress," says Susan Fitzpatrick, vice president of the James S. McDonnell Foundation in St. Louis, which funds brain cancer research. "We're starting to make headway against a very difficult type of tumor."
Typically, brain cancer is treated with surgery, radiation, and chemotherapy. All present challenges, says Howard Fine, chief of the National Cancer Institute's neuro-oncology unit, because of the brain's sensitivity. "Most other organ systems have some potentially expendable normal tissue. You can't just remove half the brain," he says. Radiation inflicts toxic side effects, and while certain drugs effectively kill cancer cells, they kill normal cells as well. The brain is protected by a natural defense system called the blood-brain barrier, which keeps toxins out but sometimes prevents drugs from entering, too.
Now, spurred by genomic research, cancer specialists are beginning to understand the physical and chemical properties that predict which drugs will break through the blood-brain barrier. Therapies that home in on specific tumor cells and spare healthy ones are being developed also; one such drug, Avastin, approved by the FDA in 2009, was the first new glioblastoma treatment in more than a decade. Avastin works by curbing the growth of new blood vessels that supply blood to tumors. "This is a tremendous advance," Fine says. "The response rate with most of our drugs is less than 5 percent. With Avastin, we're seeing upwards of 70 percent."
Imaging is improving, too, leading to better monitoring and new surgical techniques. Using functional magnetic resonance imaging to map brain activity in the area surrounding a tumor, for example, surgeons can minimize harm. "We're able to do surgery and remove tumors in areas of the brain that we previously couldn't even think about touching," Fine says. A few institutions, including the University of California, San Francisco Medical Center, are testing a technique that causes even single cancer cells to make their presence known by glowing under fluorescent light.
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